Artificial leg and knee joint therefor



0a. 3o, 1951 J, A MAZZOLA 2,573,347

ARTIFICIAL LEG AND KNEE JOINT THEREF'OR Filed July 23, 1947 lNvENToR cfoseyofazzoia.

Patented Oct. 30, 1951 ARTIFICIAL LEG AND KNEE JOINT THEREFOR.

Joseph A. Mazzola, Enaioott, N. Y.

Application July 23, 1947, Serial No. 762,94'8

6 Claims.

The present invention relates to prosthetic devices and more particularly to an articial leg construction which, when in actual use, will enable an above-the-knee amputee to accurately reproduce the normal walking gait.

It is among the principal objects of the invention to produce an artificial leg having a novel type of exible knee joint which is capable of bearing the full weight of the user at any angle of exure between the axes of the thigh and calf sections of the artificial leg construction.

Another and equally important object of the invention is to provide a leg construction of the nature outlined above which will permit changing of the angle of flexure while the weight of the user is being supported by the knee joint.

A still further object of the invention is to provide an artificial leg having a flexible knee joint which is so constructed as to permit flexing between the thigh and calf sections, in the normal manner of thigh and calf lexure, either in free fashion or under load and throughout the maximum useful angle, yet which at the same time will prevent abnormal reverse flexing and consequent collapse of the joint under the inuence of weight applied thereto.

Another object of the invention is to provide an articial leg construction of the character set forth above and having a foot section provided with a flexible toe extension which, upon flexing due to normal contact with the ground, releases the knee joint for ilexing until such time as the foot section has left the ground and the toe extension again becomes normally extended. The toe extension is also operable when the knee joint is partially flexed to release the same for further exing.

Still another object of the invention is to provide an articial leg construction having thigh, calf and foot sections, the latter including a toe extension, and in which the thigh and calf sections have interposed therebetween a resilient shock absorbing medium which operates to prevent sudden impact between these two parts when the angle of liexure becomes a straight angle and the two sections move into alignment at the end of each step cycle after the foot section leaves the ground. Similar objects of the invention reside in the provision of a resilient shock absorbing medium between the toe extension and the foot section proper and also between the foot section proper and the calf section to relieve rigidity between these parts when the same are in substantial abutting relationship.

The provision of an artificial leg possessing the features outlined above, one which is relatively simple in its construction; one which ispossessed of a minimum number of moving parts and which consequently is unlikely to get out of order; one which is rugged and durable; -one in which many of the parts may be constructed of light sheet metal stampings lthus eliminating oby jectionable overall weight; one which may be manufactured'at a low cost; one which is attractive in appearance and design; one which is silent in its operation; one which may be worn for long periods of time without discomfort to `leg constructed in accordance with the principles of the present invention. In this view certain parts have been'broken away to more clearlyV reveal the nature of the invention.

Fig. 2 is a sectional view taken substantially along the line 2--2 of Fig. 1.

Fig. 3 is an enlarged view similar to Fig. 2 with certain parts removed for the sake of clarity;

Fig. 4 is a sectional view taken substantially along the line 4-4 of Fig. 3.

Fig. 5 is a sectional view taken substantially along the line 5 5 of Fig. 1; and

Fig. 6 is a diminutive side elevational View, partially schematic in its representation, illustrating certain principles of operation associated with the invention.

In all of the above described views like characters of reference are employed to designate like parts throughout. These views show a right leg assembly. l

Referring now to the drawing in detail, the improved articial leg involves in its general vorganization a thigh section I0, a calf section I2 and a foot section I4, the latter including a toe section or extension I6 which is hinged as at I8 to the foot section proper. The leg also includes a lever 24 which is hinged as at 2B to the thigh section I0 and which, for convenience of description and claim terminology, may well be termed as the torsal or abdominal section inasmuch as this lever is actuated during relative exing movements between the torso and thigh of the user to accomplish a function that will be made clear presently.

As shownthe thigh and calf sections I0, I 2 `depend for their rigidity and their abiilty to carry a load upon the nature of their respective shell like cosmetic exterior portions. These substantially cylindrical hollow shells are patterned after the size and shape of the human limbs and are formed of a sturdy material, such as laminated wood, ber, plastic or the like, and they may constitute the main support for the various movable or stationary mechanical fittings and accessories associated with theV invention.

As shown in Fig. l, a plate ror bracket 26 is riveted as at 22 or is otherwise secured to the outside of the thigh section IIJ at the top thereof and projects a slight ldistance above the upper rim of the section. The previously mentioned lever 24, which for convenience of description of claim terminology may in itself be regarded as the torsal section of the articial l leg, is hinged as at 26 to the bracket 20 and has its upper end secured by means of a plate 28 to a pelvic band or strap 3D which is preferably formed of leather and which is padded as at 32 for the comfort of the user. The strap is adapted to be positioned around the abdomen of the user While the thigh or stump from which amputation has been made is adapted to be received in the hollow thigh section I 6. The abdomen or torso and thigh have been illustrated in dotted lines at 34 and 36, respectively. The function of the lever 24 will be made clear presently.

The thigh section I is in the form of a slight- 1y tapered hollow substantially conic section and the lower end thereof has fitted on the inside a steel or other metal ring-like insert 38 having depending therefrom a pair of ears 40 and 42 Which formv a part of a special locking hinge construction or knee joint which has been designated in its entirety at 44. The knee joint 44 also includes a pair of ears 46 and 48 which are formed on a ring-like member or sleeve 50 which surrounds and is secured to the upper end of the calf section I 2. A pin or through bolt 52 is supported at its opposite,

ends centrally in the ears 46 and 48 and extends transversely across the section and passes through the ears 40 and 42. The through bolt is pinned as at 54 against turning movement relative to the ears 46 and 46 `and is thus constrained to `move bodily with and follow the swinging movements of the calf section I2.

The bolt 52 is formed with a medial threaded section or lportion 55 and has threadedly received thereon one abutment element 56 of a clutch-like assembly whose counterpart is in the form of an extension or abutment 58 formed on the collar 42. The element 56 is provided with a pair of teeth 59 thereon 4and the member 58 is provided with a pair of similar and mating teeth 60. The surfaces of the members 58 and 60 between the extremities of the teeth are inclined as shown at 62 in Fig. 4 and afford mating inclined contact surfaces designed for engagement when thel member 56 is turned on the through bolt 52 and wedged against the member 58.

The lever 24 is formed with a rearward extension or arm 66 which is oifset to project outside the conical confines of the thigh section I0 and this extension is connected by means of a cable 68 to the element 56 on which it is wound in the manner of a drum winding. A second cable 69 winding on the member 56 is attached to one end of a coil spring and the other end of the spring is attached to an internal lug 'I2 formed on the inside of the calf section I2. 'I'he member 56 is thus biased to turn in a counterclockwise direction as viewed in Fig. 1 for mating engage- .4 mentof the teeth 59 and 66 and of the inclined surfaces 62.

From the above description it will be seen that the through bolt 52 constitutes a hinge pin or pintle by means of which the thigh and calf sections !0 and I2 are pivotally connected together. The two sections are capable of iiexing with respect to each other and, in the erect position of the artificial leg where the two sections are in substantial alignment, reverse or abnormal iiexing of the structure is prevented by means of a yieldable pad or bumper 14 which is suitably attached to the calf section and which occupies a position on the forward side of the structure between the upper rim of the calf section and the lower rim of the thigh section. The pad I4 may be formed of any suitable yieldable material such as rubber and it serves to prevent sudden impact between the rim portions of the' two sections and consequently to eliminate sudden impact between the two parts and consequent sound and vibration.

The strength of the spring 'I0 is relatively great and as a consequence the knee joint section or element 56 is biased on the threaded portion 55v of the bolt 52 so as to bear against the section 58 with a fair degree of pressure and to resist any normal camming action that would ordinarily tend to occur if a torque were to be applied to either section tending to cause relative flexing between them. This resistance to such torque is made possible by virtue of the relative small pitch of the threads on the portion 55 of the bolt 52. Thus, when the thigh and calf sections ID and I2 are in alignment and the weight of the user rests upon the structure any tendency of the sections to ex relative to each other is prevented by the inability of the element 56 to yield or back up, so to speak, on the threads 55. The structure in this erect position is a rigid one and is not subject to collapse. The spring 'l0 is provided primarily to return the element 56 to its position of engagement with its counterpart element 58 when the thigh and calf sections are straightened into alignment.

In order to permit knee exure during the normal walking gait, considering only the arrangement of parts thus far described, fiexure of the toe extension I6 due to contact'with the ground or other supporting surface will cause clockwise movement of the lever 92 and the consequent application of tension to the cord 94. The element 56 will thus be turned in a clockwise direction as viewed in Fig. 1 and, in so moving, this element will be backed away from its counterpart element 58 on the threads 55. Such motion of the element 56 will also serve to separate the teeth 59 and 6B a predetermined distance, clepending upon the extent of lrelative flexure between the torso and the thigh section I0. Inasmuch as, during this relative movement between the two clutch elements 56 and 5B, the inclined surfaces 62 thereof become separated, the calf section I2 will then be free to swing rearwardly relative to the thigh section Ill until such time as the lost motion between the two elements 56 and 58 is taken up on the action of the spring 'I0 and cord 69 after the foot section has left the ground or supporting surface.

Loosening of the knee clutch or joint 44 to permit knee iiexing may also be caused by the simple expedient of swinging the thigh or stump 36 forwardly and this motion will have the same effect as bending the body or torso forwardly.

Either of these motions will apply a tension to the 5 cord .08 to unwind'the latter from the Vrotatable clutch element 5.8 .and separate the clutch teeth 59, 60 to permit free flexing of the :knee joint. Such .anatomical movements on .the part of the amputee will be resorted to when :mounting a flight of steps or an incline.

When proceeding up a .steep incline :or mounting a staircase, the extent of forward inclination of the body and of forward swinging elevation of the thigh will be .quite marked. The amount of elevation which it is desired to .attain at each step will be governed by the relative amount of flexing between the body and thigh performed by the user of the artificial leg and thus with a little experience various grades of elevation may successfully be encountered.

The foot section proper I 4 may be in the form of a .substantially solid block-like structure constructed of wood, plastic material, light metal or other suitable material. As shown in Fig. l, an insert or block 8B is embedded .in the foot section and is provided with an upwardly extending ear 82 substantially centrally of the section. .A bolt or pintle pin 8d is securedrin the .ear :82 and serves to support thereon a pair of relatively heavy metal straps 86 which are bolted or -otherwise secured as at Se t the opposite -sides of the calf section I2. The calf sectionis thus hingedly supported from and connected to the foot vsection Id. A rubber shock absorbing medium 89 is inserted in a recess formed in the block 80 and bears against the underneath edges of the two strap members 8S.

A rock shaft 9E! extends Iacross the calf section I2 and is supported at its ends in the two straps 85.5 adjacent the top thereon while a bell crank lever 92 is pivoted medially on the shaft B0.. One arm of the lever 02 projects forwardly and has secured thereto the lower end of .a cord 94. The cord S extends upwardly and is 'wound around and secured to the clutch element 56 as shown in Fig. 2. vThe direction of winding ofthe cord 94 on the clutch element 5t is :such that clockwise turning movement of the lever .92 will apply tension to the cord 91% to `rotatethe element 56 in a clockwise direction as shown in Fig. l to thus cause this element to move away from its counterpart element 58 and disengage the clutch teeth 59, 60.

The lever Q2 is provided with a downwardly extending arm, the lower end of which is pivotally connected to a thrust rod 98 which is inclined forwardly and downwardly Vand the forward end of which loosely rests upon a rubber `insert |00 which is interposed between the toe extension I6 and the foot section proper |45 with its extreme outer end occupying a -position slightly rearwardly of the toe extension I6 and normally Vout of contact therewith.

It will be seen from the above description of parts that during the normal walking gait, when the calf section i2 assumes a forwardly inclined position with the toe extension I6 resting squarely upon the ground and with the heel portion |02 of the foot section proper Ill elevated, the rubber insert I0@ will become compressed while,. at the same time, one surface of the toe extension I6 will engage the forward end of the thrust lever 03 and apply a torque to the bell crank lever 92, tending to rock this lever in a clockwise direction. Such movement of the lever 92 will apply a tension to the cord 06, thus unwinding the same from the element 5t and turning the latter so as to disengage the clutch teeth 59 and .B0 to provide a lost motion between the two `parts 56 .and `58 which :may be taken up by further flexing lof .the knee joint.

A yieldable insert `|10 is .disposed between the lower rim of the calf section I2 and the heel portion |02 of the foot section `proper `Ill to kprevent looseness of the latter .section on the calf section and to take up any .shocks that might .exist and to eliminate any sudden impact and consequent shock that might exist during normal relative movements between these two parts. A cord |08 has its ends attached in any suitable manner to the foot and calf sections and thus serves to apply a plantar or forward tilting movement to the foot section I4 during walking to elevate the heel portion |02 from the ground and permit flexing of the toe section I6.

From the above description it will be seen that there has been provided a prosthetic device in the formof an artificial leg having a novel type of locking knee action which will support the entire weight of the body at any angle of iiexure between the thigh and calf sections of the structure, yet which, at the same time, will permit ready release of the locking action when the structure is relieved of its supporting weight. The degree of knee iiexure is adapted to be controlled at the will of the user, either by wilful forward inclination of the torso by application of pressure to the supporting surface or ground by the flexible .toe extension which forms a part of the foot section, or by any such combination of these two factors as is found to be a part of the normal gait of the user.

It will be appreciated that the present prosthetic device is, for reasonspreviously outlined,

adapted for use in the normal manner of locomotion for walking operations, both on level and inclined surfaces as well as for mounting stepped surfaces, such as a flight of stairs. The artificial .leg is also adapted to accommodate itself for sitting positions wherein the thigh section thereof remains substantially horizontal while the calf section assumes a substantially vertical position. This latter feature is made possible by virtue of :the fact that in a .normal sitting position the axis of the abdominal or pelvic regions assumes approximately a ninety degree angle with the axis of the thigh section. In the artificial leg structure described above, this results in a wide swingying movement of the lever 24 and a consequent large displacement of the rotatable portion or section 5B of the locking knee joint. Such a displacement releases the calf section for swinging movement throughout an angle of at least ninety degrees which is sufficient to permit the calf section to assume a vertical position with the foot section I4 resting on the floor.

When ina sitting position the amputee may' even exceed a ninety-degree iiexure between the thigh and lcalf section and assume a position with the calf section inclined rearwardly and with the foot section I4 beneath the chair or other support and directly beneath the vertical axis of the torso. .In other words, the seated amputee may even draw his foot in beneath the chair upon which he isseated. Such a position is often normally assumed and in the articial leg structure this is made possible by flexure of the toe extension I6 and raising ofthe heel portion |02 from the floor. Such a condition further releases the knee clutch 44 through the action of the cable 94 as previously explained.

While there have been shown and described and pointed out the Vfundamental novel features yof the invention, as applied to a preferred-fembodiment, it will be understood that various omissions and substitutions and changes in the form and details of the device illustrated and in its operation may be made by those skilled in the art without departing from the spirit of the invention. It is the intention, therefore, to be limited only as indicated by the scope of the following claims.

What is claimed is:

1. In an artiiicial leg construction, a thigh section and a calf section, a pintle element secured to one of said sections and pivotally connecting the two sections together with relative flexing movement from a position of substantial alignment to a position of acute angle flexure, an abutment or clutch element mounted on the other section, a second abutment of clutch element, said pintle element -being formed with threads thereon upon which said second abutment element is threadedly received, yieldable means normally applying a torque to said second abutment element in a direction to urge the same into engagement with said rst abutment element to prevent initial flexing between the sections when they are in substantial alignment, and means operable by independent movement of an anatomical portion of the body of the user for applying a predetermined amount of reverse or counter torque to said second abutment element to remove the latter from said engagement with said other abutment and permit a commensurate amount of relative flexing between said sections.

2. In an artificial leg construction, a thigh section and a calf section, a pintle element secured to one of said sections and pivotally connecting the two sections together for relative exing movement from a position of substantial alignment to a position of acute angle fiexure, an abutment or clutch element mounted on the other section, a second abutment or clutch element, said pintle element being formed with threads thereon upon which said second abutment element is threadedly received, yieldable means normally applying a torque to said second abutment element in a direction to urge the same on said threads into engagement with said rst abutment element to prevent initial flexing between the sections when they are in substantial alignment, and means operable upon relative flexing movement between the torsal axis of the user and the axis of said thigh section for applying reverse or counter torque to said second abutment element to remove the latter from engagement with said other abutment element and permit a degree of relative flexing between said sections which is proportionate to the degree of relative iiexing movement between said torsal axis and the axis of said thigh section.

3. In an artiiicial leg construction, a thigh section and a calf section, a pintle element secured to one of said sections and pivotally connecting the two sections together for relative flexing movement from a position of substantial alignment to a position of acute angle flexure, an abutment or clutch element mounted on the other section, a second abutment or clutch element, said pintle element being formed with threads thereon upon which said second abutment element is threadedly received, yieldable means normally applying a torque to said second abutment element in a direction to urge the same along said threads into engagement with said first abutment element to prevent initial flexing between the sections when they are in substantial alignment, a cord secured to said second abutment element and operable upon the application of tension thereto to apply a reverse or counter torque to the latter to remove the same from engagement with said other abutment element and permit a predetermined amount o1' relative iiexing between said sections and means for attaching said cord to an anatomical portion of the body of the user whereby movement of said anatomical portion in one direction relative to said thigh section will apply tension to said cord.

4. In an articial leg construction, a thigh section and a calf section, a pintle element secured to one of said sections and pivotally connecting the two sections together for relative flexing movement from a position of substantial alignment to a position of acute angle lexure, an abutment or clutch element mounted on the other section, a second abutment or clutch element, said pintle element being formed with threads thereon upon which said second abutment element is threadedly received, yieldable means normally applying a torque to said second abutment element in a direction to urge the same into engagement with said first abutment element to prevent initial iiexing between the sections when they are in substantial alignment, a bell crank lever pivoted to said thigh section, means operatively connecting an arm of said lever to the pelvic region of the user whereby forward inclination of the torso will cause inclination of said lever, a cord connected to another arm of said lever and to said second abutment member whereby movement of said lever to its inclined position will apply reverse or counter torque to said latter element to remove the same from engagement with said other abutment element and permit a predetermined amount of relative exing between said sections.

5. In an articial leg construction, a thigh section and a calf section, a pintle element secured to one of said sections and pivotally connecting the two sections together for relative flexing movement from a position of substantial alignment to a position of acute angle flexure, an abutment or clutch element mounted on the other section, a second abutment or clutch element, said pintle element being formed with threads thereon upon which said second abutment element is threadedly received, yieldable means normally applying a torque to said second abutment element in a direction to urge the same into engagement with said rst abutment element to prevent initial exing between the sections when they are in substantial alignment, a foot section mounted on the lower extremity of said calf section and having a toe extension capable of exing movements relative thereto upon contact with and pressure of the latter on the ground and means operable upon relative flexing between said toe extension and foot section for applying reverse or counter torque to said second abutment element to remove the latter from engagement with said other abutment and permit a predetermined amount of relative flexing between said sections.

6. In an artificial leg construction, a thigh section and a calf section, a pintle element secured to one of said sections and pivotally connecting the two sections together for relative flexing movement from a position of substantial alignment to a position of acute angle flexure, an abutment or clutch element mounted on the other section, a second abutment or clutch element, said pintle element being formed with threads thereon upon which said second abut- 9 ment element is threadedly received, yieldable means normally applying a torque to said second abutment element in a direction to urge the same into engagement with said rst abutment element to prevent initial flexing between the sections when they are in substantial alignment, a foot section secured to the lower extremity of said calf section and having a toe extension capable of flexing movement relative to the foot section, a bell crank lever pivoted to said calf section, means operatively connecting said toe extension and bell crank lever whereby flexing of the former will cause rocking movement of the latter, and means operatively connecting said bell crank lever and second abutment element whereby rocking of the lever will apply reverse or counter torque to said second abutment element to remove the latter from engagement with said other element and permit a predetermined flexing between the thigh and calf sections.

JOSEPH A. MAZZOLA.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS 10 Number Name Date 1,722,017 Rowley July 23, 1929 2,305,291 Filippi Dec. 15, 1942 FOREIGN PATENTS 16 Number Country Date 140,660 Great Britain Apr. 1, 1920 158,096 Great Britain Jan. 31, 1921 203,591 Great Britain Sept. 13, 1923 

